Objective: To estimate the minimum clinically important difference (MCID) for several pain measures obtained from the Brief Pain Inventory (BPI) for patients with fibromyalgia.
Methods: Data were pooled across 12-week treatment periods from 4 randomized, double-blind, placebo-controlled studies designed to evaluate the safety and efficacy of duloxetine for the treatment of fibromyalgia.
Each study enrolled subjects with American College of Rheumatology-defined fibromyalgia who presented with moderate to severe pain.
The MCIDs for the BPI average pain item score and the BPI severity score (the mean of the BPI pain scale values: right now, average, least, and worst), were estimated by anchoring against the Patient Global Impression of Improvement (PGI-I) scale.
• The anchor-based MCIDs for the BPI average pain item and severity scores were 2.1 and 2.2 points, respectively.
• These MCIDs correspond to 32.3% and 34.2% reductions from baseline in scores.
Conclusion: In these analyses, the MCIDs for several pain measures obtained from the BPI were similar, approximately 2 points and corresponded to a 30%-35% improvement from baseline at endpoint. These findings may be beneficial for use in designing clinical trials in which the BPI is used to evaluate improvements in pain severity.
Source: Arthritis Care & Research, Feb 11, 2011. DOI: 10.1002/acr.20449, by Mease PJ, Spaeth M, Clauw DJ, Arnold LM, Bradley LA, Russell IJ, Kaidasz DK, Walker DJ, Chappell AS. Seattle Rheumatology Associates, Seattle, Washington;. Practice for Internal Medicine / Rheumatology, Graefelfing/Munich, GD; University of Michigan Medical Center, Ann Arbor, Michigan; University of Cincinnati College of Medicine, Cincinnati, Ohio; University of Alabama at Birmingham, Birmingham, Alabama; University of Texas Health Science Center, San Antonio, Texas; PGxHealth LLC, New Haven, Connecticut; Lilly Research Laboratories, and Indiana University School of Medicine, Indianapolis, Indiana, USA. [Email: firstname.lastname@example.org]